1. Basic Electrical Engineering
Lecture # 01
Course Instructor:
Engr. Sana Ziafat

2. Grading Policy Final Exam: 40% Mid term Exam 20% Assignments 5%
Quizzes: %
Labs %

3. Quizzes may be announced or unannounced.
Exams are closed-book and extremely time limited.
Exams consist of design questions, numerical, maybe true-false and short answer questions.

4. TEXT BOOKS Electric Circuits by J.W. Nilson & Susan A. Rediel
Schaum’s Outlines
by: M Nahvi

5. Objectives of the Course
To impart the basic knowledge of electric circuits
To know about various measuring instruments
To introduce basic electrical concepts and laws

6. Agenda Basics of electric circuits Measuring system/SI Unit
Ideal Basic circuit element
Basic electric circuit quantities

7. Measurement You are making a measurement when you Check you weight
Read your watch
Take your temperature
What kinds of measurements did you make today?

8. Standards of Measurement
When we measure, we use a measuring tool to compare some dimension of an object to a standard.

9. Some Tools for Measurement

10. Learning Check A. temperature ____________________
From the previous slide, state the tool (s) you would use to measure
A. temperature ____________________
B. volume ____________________
____________________
C. time ____________________
D. weight ____________________

11. Solution
From the previous slide, state the tool (s) you would use to measure A. temperature thermometer B. volume measuring cup, graduated cylinder C. time watch D. weight scale

12. International System Of Units
Is a decimal system based on 10
Used in most of the world
Used by scientists and hospitals
Based on seven defined quantities
Defined quantities are combined to form derived units.

14. Units in the Metric System
length meter m
volume liter L
mass gram g
temperature Kelvin K

15. In every measurement there is a Unit from measuring device
Stating a Measurement
In every measurement there is a
Number
followed by a
Unit from measuring device

16. Learning Check A. The patient’s temperature is 102°F.
What is the unit of measurement in each of the following examples?
A. The patient’s temperature is 102°F.
B. The sack holds 5 lbs of potatoes.
C. It is 8 miles from your house to school.
D. The bottle holds 2 L of orange soda.

17. Solution A. °F (degrees Fahrenheit) B. lbs (pounds) C. miles
D. L (liters)

18. Learning Check
Identify the measurement in SI units. A. John’s height is 1) 1.5 yards 2) 6 feet 3) 2 meters B. The volume of saline in the IV bottle is 1) 1 liters 2) 1 quart 3) 2 pints C. The mass of a lemon is 1) 12 ounces 2) 145 grams 3) 0.6 pounds

19. Solution
A. John’s height is 3) 2 meters B. The volume of saline in the IV bottle is 1) 1 liter C. The mass of a lemon is 2) 145 grams

20. Derived Units
Force equals mass time acceleration: newton is defined as unbalanced force that imparts an acceleration of 1 meter per second equal to a 1 kilogram mass.
Work results when force works over a distance: Joule is equivalent to newton-meter
Power is rate at which power is done: watt is joule per second

22. Electric Circuits Interconnection of electrical components
Elementary quantities in the analysis of electric circuits are:
1. electric current
2. voltage

23. Electric charge and current
Charge is bipolar, meaning electrical effects are described in terms of positive and negative charges.
Time rate of change of charge is known as electric current:
i(t) = dq(t)/dt
where i and q are current and charge respectively.
Basic unit of charge is ampere (columb per second)
One ampere is equivalent to 1 columb charge moving across a fixed surface in 1 second.

24. Volatge
If a unit positive charge is moved between two points then the energy required to move it is the difference in energy level between the two points and is defined as voltage.
v= dw/dq, where as ‘w’ and ‘q’ are work and charge respectively
Unit of voltage is volts, 1 volt= 1joule/coulomb= newton-meter/coulomb

25. Basic Circuit Element It has only two terminals
It cant be further sub divided
It is described mathematically in terms of current and voltage

26. Passive sign convention
Whenever the direction for the current in an element is in the direction of the reference voltage drop across the element use a positive sign in any expression that relates the voltage to the current

27. Circuit Measurements
Electric Current - Flow of electrons through a material
Electrical Potential –
Similar to potential energy (lifting something higher against the force of gravity gives it greater potential to do work, increasing its potential energy.)
When given the opportunity, objects will move from higher potential energy to an area of lower potential energy
Electrical potential is related to their electrical fields and not to height – as electrons build up on one side they “want” to flow to an area w/ less potential

28. Voltage Voltage – causes current to flow through an electrical circuit
Volt – unit of measure to measure this potential
A Voltage Source (battery or generator) is required to maintain the electrical potential in a circuit.

29. Electrical Current
Water flowing thru a pipe depends on more than the angle of the pipe. It also depends on the length of the pipe, diameter of the pipe and if the pipe is clogged or open.
Electrical Current is measured in Amperes
Amount of Electrical Current ( amps) depends on more than just Voltage, it depends on the Resistance found in the circuit.

30. Energy and power
Output of a system is often non electrical and is expressed in terms of energy or power.
p=dw/dt
Unit is watt and watt= joule/sec
p=vi….. How?????????

31. Readings Chapter 1: 1.2, 1.4, 1.5, 1.6 (Electric Circuits)
By James W. Nilson

32. Q & A